This episode is a long one, but so good, with a lengthy visit with Craig Cogil at the National Weather Service in Johnston. We're so grateful for all of Craig's time and insights! Forecast Discussion A system moving through tomorrow will bring snow to northern Iowa, with 1-2 inches expected north of Highway 20. Strong winds and colder air will follow. The 8-14 day outlook shows high confidence in above-average temperatures, potentially reaching the 40s. There's a slight chance of above-average precipitation, likely in liquid form due to warmer temperatures. Climate Trends December has been warming in recent years, with less snow and more mixed precipitation events. The beginning of December 2024 has been close to normal in temperature and slightly drier than average. Recent Weather Events An ice storm occurred on Friday, December 13th, affecting areas including Omaha, Des Moines, and Ames. The timing of the ice storm during evening commute in Omaha led to significant impacts. Forecasting Challenges Predicting mixed precipitation (sleet, freezing rain) is particularly challenging due to the complexity of temperature profiles and freezing lines. Small changes in temperature or location can significantly affect the type of precipitation experienced. Latent heat release during phase transitions can complicate forecasts by warming surface air more quickly than anticipated.   Tornado Climatology and Technology The conversation then shifts to discussing tornado climatology and the evolution of weather technology. The official tornado climatology database started in 1950. Early records (1950s-1970s) only noted tornado occurrences without ratings. In the mid-1970s, a project retroactively rated tornadoes from 1950 onwards using newspaper archives and photos The Fujita scale for rating tornadoes was introduced in the mid-1970s There's been an apparent increase in tornado numbers over time, largely due to improved detection and reporting methods Radar Technology Evolution Weather radar technology evolved from repurposed World War II equipment. The first dedicated weather radar network, WSR-57, was introduced in 1957. This was followed by WSR-74 in 1974, which came in different frequency bands (S-band and C-band) S-band radars (10 cm wavelength) are better at penetrating heavy precipitation, while C-band radars (5 cm wavelength) are more easily attenuated  

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